While silicon is the industry common semiconductor in many electric units, which includes the photovoltaic cells that pv panels utilize to convert sunlight into electricity, it is not really the most effective product readily available. For instance, the semiconductor gallium arsenide and associated compound semiconductors give practically two times the effectiveness as silicon in solar devices, however they are rarely used in utility-scale applications because of their excessive production value.

University. of I. (http://illinois.edu/) teachers J. Rogers and X. Li researched lower-cost techniques to create thin films of gallium arsenide which also made possible versatility in the types of products they can be integrated into.

If you can decrease significantly the cost of gallium arsenide and other compound semiconductors, then you could increase their variety of applications.

Generally, gallium arsenide is transferred in an individual thin layer on a small wafer. Either the wanted unit is produced directly on the wafer, or the semiconductor-coated wafer is cut up into chips of the desired dimension. The Illinois group made the decision to deposit multiple layers of the material on a single wafer, creating a layered, "pancake" stack of gallium arsenide thin films.

If you grow ten levels in a single growth, you simply have to fill the wafer a single time. If you do this in ten growths, loading and unloading with temp ramp-up as well as ramp-down get a lot of time. If you take into account exactly what is needed for every growth - the machine, the planning, the period, the workers - the overhead saving this technique gives is a substantial cost decrease.

Following the researchers individually peel off the layers and transfer them. To achieve this, the stacks alternate levels of aluminum arsenide with the gallium arsenide. Bathing the stacks in a solution of acid and an oxidizing agent dissolves the layers of aluminum arsenide, freeing the individual small sheets of gallium arsenide. A soft stamp-like system picks up the layers, just one at a time from the top down, for exchange to one more substrate - glass, plastic-type or silicon, based on the application. Then the wafer could be used again for another growth.

By performing this it's possible to make much more material much more rapidly and a lot more cost efficiently. This process could make bulk quantities of material, as opposed to just the thin single-layer manner in which it is usually grown.

Freeing the material from the wafer additionally starts the probability of flexible, thin-film electronics made with gallium arsenide or some other high-speed semiconductors. To make units which can conform but still maintain high efficiency, that's significant.

In a paper shared online May twenty in the newspaper Nature (http://www.nature.com/), the group explains its procedures and displays three kinds of products using gallium arsenide chips made in multilayer stacks: light devices, high-speed transistors and solar cells. The authors also provide a detailed cost evaluation.

One more advantage of the multilayer approach is the release from area constraints, particularly important for photo voltaic cells. As the levels are taken out from the stack, they can be laid out side-by-side on one more substrate to produce a much bigger surface area, whereas the standard single-layer procedure limits area to the dimension of the wafer.

For photovoltaics, you need large area coverage to catch as much sunlight as achievable. In an extreme situation we might increase sufficient layers to have 10 times the area of the traditional.

Up coming, the group programs to investigate more potential device applications and other semiconductor resources that could adapt to multilayer growth.

About the Article author - Shannon Combs gives advice for the residential solar power design weblog, her personal hobby weblog centered on tips to help home owners to conserve energy with sun power.